Venetian blinds comprise a plurality of slats horizontally supported by two or more ladders extending between a head or top rail and a foot or bottom rail. A chord is provided for elevating or lowering, the blind to a lowermost or intermediate position.
It is often desirable to tilt the slats in order to darken a room to meet the requirements of individuals present in the room, or to prevent direct sun light from entering the room so as to avoid dazzling and possible damages caused by direct sun light, in particular by the ultra violet rays. Tilting the slats into a suitable angle also prevents viewing into the room through a window. For these and other reasons, there is usually provided a tilting mechanism for tilting the slats about a horizontal axis extending through the slats.
A typical tilting mechanism comprises a worm gear assembly fitted within the top rail and manipulable by a rod extending downwards. However, such tilting mechanisms enables only tilting all the slats of the blind in either one or an other direction. Drawback of this arrangement resides in that it is not possible to tilt some of the blinds in one direction, while other slats are tilted in an other direction so as to allow, on the one hand, sufficient light enter the room, and on the other hand to block direct sun light and to prevent viewing the room from the outside.
Several arrangements have been suggested for tilting a first group of the slats in one direction, while tilting the remaining slats in an other direction, typically in a complimentary angle with respect to the first group of salts.
European Patent Application published as 620355 A1 discloses a tilting assembly comprising an additional operating chord passing over pulleys fitted within the head rail and attached to a desired division of slats, whereby the extent of pulling the additional chord dictates the tilting angle of the division of slats independently from the remaining slats.
The arrangement of the above disclosed Patent Application involves several drawbacks. One problem is that the plurality of chords are likely to tangle with one another. Another drawback is that special arresting are required for fixing the length of the additional chord in order to set the desired tilt angle.
U.S. Pat. No. 5,402,840 discloses a venetian blind in which the slats are divided into upper and lower portions by a divider comprising a spacer and a retainer, which serve to shorten the working length of the tilt adjusting ladders on either the inside or outside of the blind, altering the tilt of the slats of the lower portion so as to be more closed or more open with respect to the slats of the upper portion., depending on the adjustment of the tilt control ladder.
A disadvantage of the device according to that Patent is that a dividing element must be articulated to at least two ladders of the blind and it may frequently happen that the dividing elements are articulated at different heights or unevenly tensioned, thus entailing tilting the blinds not parallel to one another. Displacing each of the at least two divider elements while taking care of correct alignment, is a procedure which might be complex for children or elderly people, and even more so, is impossible for handicaps. It will further be appreciated that displacing the dividing elements is somewhat a hassle.
U.S. Pat. No. 5,119,868, discloses a venetian blind in which the slats of an upper section and the slats of the lower section are separately adjusted using a three-position switch attached to a rotatable and horizontally movable rod. Depending on the position of the switch, rotation of the control rod adjusts the tilt of the slats of either the upper or the lower slat section.
It is an object of the present invention to provide a novel and improved venetian blind in which the above disadvantages are essentially reduced or overcome. It is a further object of the invention to provide an improved tilting device for a Venetian blind.